Difficulties arise in achieving effective deposition of cosmetic agents onto skin or hair when the cosmetic agent is delivered by means of incorporation into rinse-off compositions, typically hair and body shampoos, conditioners and the like. Frequently, cosmetic agents, particularly those which are water- and/or surfactant-soluble or -solubilizable, are preferentially rinsed away from the intended site of deposition, rather than being deposited thereat.
Conventional rinse-off compositions therefore have limited efficacy as vehicles for deposition of cosmetic agents and also lead to non-cost-effective use of and waste of cosmetic raw materials.
Water- and/or surfactant-insoluble or -insolubilizable cosmetic agents, on the other hand, also face problems, because their insolubility makes it difficult to achieve stable incorporation at the desired levels, yet giving an adequate degree of deposition of the cosmetic agent from the composition at the intended site.
Cosmetic agents which are soluble or solubilizable in only one of water and surfactant share all of the above mentioned problems, but to intermediate degrees.
It is an object of the present invention to ameliorate the aforementioned disadvantages and to facilitate and/or enhance deposition of cosmetic agents from cosmetic compositions, particularly rinse-off compositions.
One system by which deposition of cosmetic agents from rinse-off cosmetic compositions may be enhanced is disclosed in our co-pending United Kingdom patent application No 9200764.0, in which there is disclosed a rinse-off cleansing composition including one or more surfactant-soluble cosmetic agents, e.g. a sunscreen oil, for deposition onto hair or skin, the composition comprising a stable emulsion having a continuous phase comprising one or more surfactants and an internal phase comprising one or more oil materials, e.g. a silicone oil, wherein the internal oil phase contains the said one or more surfactant-soluble cosmetic agents.
In a different field, for the purpose of topically administering, especially with controlled release, a variety of cosmetically or pharmaceutically active agents, porous microparticles of a polymeric material in which the active agent is impregnated have been utilized as a carrier. Such a system is described for example in EP-A-0306236. Here the disclosed microparticles have a preferred particle size of between 1 and 100 microns, in order to give the compositions in which the microparticles are incorporated aesthetic appeal, particularly smooth feel to the touch. However, the technology relied upon for this type of delivery system tends to be expensive and involves the use of organic solvents, which make the technology environmentally unfriendly and may present safety problems.
During our investigations into the possibility of utilizing particulate polymeric materials as carriers for cosmetic agents to be deposited onto skin or hair from rinse-off cosmetic compositions, it was found that the types of system described in EP-A-0306236 are technically unsuitable, firstly because the disclosed cross-linked polymers are poor film formers and are thus difficult to deposit effectively onto hair or skin, and secondly because the described polymer particles give rise to cosmetic compositions which are not aesthetically pleasing, e.g. they are cloudy.
Also disclosed in the art is the use of certain polymer lattices in combination with cationic polymers for treating the hair, skin or nails, for example as disclosed in U.S. Pat. No. 4,710,374 (corresponding to GB-A-2114580). Here the latex is an anionic latex and when used in combination with a variety of cationic polymers which condition the hair, imparts properties of liveliness, volume, stiffness and hold of the hair which persist for a longer period of time compared with that obtained with known anionic polymers instead of the anionic latices.
The application of hair setting or styling polymers to hair for such cosmetic purposes by way of deposition from cosmetic compositions comprising such polymers in the form of micro-particle latices is also known from U.S. Pat. No. 4,798,721, U.S. Pat. No. 4,985,239 and U.S. Pat. No. 4,753,793. In these references, however, the aim is to apply to the hair the polymer itself for the benefit it imparts and there is no disclosure or teaching of any association between the polymer latex particles and any additional cosmetic substances which may be present in the disclosed compositions.